Families are the primary source of care for children, a safety net for young adults, and the preferred source of care for older adults. The relationship between parents and children, in particular, represents one of the most significant family ties and a major source of support over the life course. Over time, parent-child relationships have become even more salient due to increases in longevity, which provides opportunities for longer and more meaningful exchanges between parents and their adult children and grandchildren. Today, family support is central to the wellbeing of both older parents as they age and become frail, as well as their adult children as they establish themselves economically and professionally, and as they have children of their own. We live, however, in an era of family complexity, and changes in family composition over the last decades likely influence resource sharing between parents and children ? but, scholars are yet not sure how or why. Given the importance of private transfers within American families, this dissertation will rely on quantitative and qualitative approaches to investigate intergenerational support among older parents and adult children/grandchildren in an increasingly common type of family in the U.S: older stepfamilies. It posits that parents? marriage histories taken as a whole, and the quality of parents? remarriages are key in determining intergenerational support dynamics between parents and adult children later in life.Additionally, it will focus on socioeconomic differences in family dynamics to further understand whether characteristics, vulnerabilities, and pathways to success in a complex family environment are different for socioeconomically advantaged and disadvantaged families.This research will add to scholarship on how family complexity shapes intergenerational support in the context of low-income families. It will, therefore, shed light on how to promote positive, nurturing, and supportive marriages and family relationships in the context of family complexity and socioeconomic disadvantage. Findings will be of immediate use to the local jurisdiction and community partners, who have expressed interest in developing programs or targeting services to the needs of low-income mature stepfamilies.